Field of the Invention
The present teaching relates to a method for inspecting a substrate and a substrate inspection apparatus utilized for three-dimensional lamination and the like. The present teaching further relates to an exposure system and a method for producing semiconductor devices utilizing the inspection method and the inspection apparatus.
Description of the Related Art
As the miniaturization of semiconductors is said to be approaching its limit, three-dimensional lamination of semiconductor chips has the advantages in improving performance, saving power, saving space, and the like. Hence, it is rapidly spreading as a means for increasing added value abreast with the miniaturization of semiconductors. The three-dimensional lamination is a technique for laminating semiconductor chips which have been made as thin as approximately 10 to 50 μm. The upper and lower chips are electrically connected by a plurality of electrodes through the chips (TSV: Through-Silicon Via). In this manner, because it is possible to electrically connect the chips in a short distance, compared with the conventional SIP (System in a Package) connecting the chips aligned horizontally, increasing the working speed of elements, and saving the power and space can be achieved.
There are various methods for forming TSVs. For example, the TSVs may be formed either before or after the elements in a semiconductor chip are formed. However, in either case, the TSVs are formed by making deep and fine holes in a wafer (a silicon substrate), covering the sidewall of the holes with an insulating film, and then filling up the holes with a highly-conductive substance such as copper and the like. At the time, it is important to inspect the wafer during and after forming the TSVs. These inspections are carried out by breaking up the wafer to observe the wafer with a SEM (Scanning Electron Microscope) or a TEM (Transmission Electron Microscope). Although it is possible to observe the actual shape of the cross section with this method, the inspection is destructive and time-consuming.
On the other hand, there is another method which utilizes a microscope and the like to observe the wafer surface. However, in this manner it is merely possible to confirm the state of the wafer surface. Further, although microscopes utilizing infrared light are also applied to observe the transmission image, because the region observable at one time is extremely small, it is impractical to inspect the TSVs of the entire wafer surface with this method. Further, because the transmission image from one side is observed, it is difficult to detect a minute and tridimensional change in profile with this method.
However, there is a technique for inspecting the repetitive pattern formed in a semiconductor wafer by detecting intensity of diffracted light, changes in polarized state, and the like (see U.S. Pat. No. 7,298,471, for example). According to this method, it is possible to inspect a large area in a short time, and detect abnormities, with a high sensitivity in a short time, due to the focus variation or dose (exposure energy) variation of the exposure device for forming the pattern as well as abnormities due to the malfunction or maladjustment of the processing device.